1. From the Covid-19 Response Team, Centers for Disease Control and Prevention (S.M.O., A.M.P., L.D.Z., A.P.C., M.M.P.), and the Center for Childhood Infections and Vaccines of Children’s Healthcare of Atlanta and the Department of Pediatrics, Emory University School of Medicine (S.K.) — both in Atlanta; the Department of Anesthesiology, Critical Care, and Pain Medicine, Boston Children’s Hospital (M.M.N., A.G.R.), and the Departments of Anaesthesia and Pediatrics, Harvard Medical School (A.G.R.) — both in...